1. Field of the Invention
This invention relates to a novel reaction product composition, an ORI-inhibIted motor fuel composition, a bi functional deposit- and ORI-inhibited motor fuel composition, and a precipitation-resistant concentrate formulation for use in motor fuel compositions. More particularly, this invention relates to a composition obtained by reacting a hydrocarbyl-substituted dibasic acid anhydride and a polyoxyalkylene diamine, an ORI-inhibited motor fuel composition comprising a base fuel containing the reaction product of (i) a hydrocarbyl-substituted dibasic acid anhydride and a (ii) polyoxyalkylene diamine and an optional polymeric component which is a polyolefin polymer/copolymer or the corresponding aminated or hydrogenated polymer/copolymer, or mixtures thereof, of a C.sub.2 -C.sub.10 hydrocarbon. The instant invention also relates to additive concentrates of the abovedescribed components in admixture with a hydrocarbon solvent which facilitates introduction of the concentrate into a motor fuel composition. Such concentrates are precipitation-resistant, thereby enhancing the storage stability of the concentrate.
2. Information Disclosure Statement
Combustion of a hydrocarbon motor fuel in an internal combustion engine generally results in the formation and accumulation of deposits on various parts of the combustion chamber as well as on the fuel intake and exhaust systems of the engine. The presence of deposits in the combustion chamber seriously reduces the operating efficiency of the engine. First, deposit accumulation within the combustion chamber inhibits heat transfer between the chamber and the engine cooling system. This leads to higher temperatures within the combustion chamber, resulting in increases in the end gas temperature of the incoming charge. Consequently, end gas auto-ignition occurs, which causes engine knock. In addition, the accumulation of deposits within the combustion chamber reduces the volume of the combustion zone, causing a higher than design compression ratio in the engine. This, in turn, also results in serious engine knocking. A knocking engine does not effectively utilize the energy of combustion. Moreover, a prolonged period of engine knocking will cause stress fatigue and wear in vital parts of the engine. The above-described phenomenon is characteristic of gasoline powered internal combustion engines. It is usually overcome by employing a higher octane gasoline for powering the engine, and hence has become known as the engine octane requirement increase (ORI) phenomenon. It would therefore be highly advantageous if engine ORI could be substantially reduced or eliminated by preventing or modifying deposit formation in the combustion chambers of the engine.
Another problem common to internal combustion engines relates to the accumulation of deposits in the carburetor which tend to restrict the flow of air through the carburetor at idle and at low speed, resulting in an overrich fuel mixture. This condition also promotes incomplete fuel combustion and leads to rough engine idling and engine stalling. Excessive hydrocarbon and carbon monoxide exhaust emissions are also produced under these conditions. It would therefore be desirable from the standpoint of engine operability and overall air quality to provide a motor fuel composition which minimizes or overcomes the above-described problems.
A third problem common to internal combustion engines is the formation of intake valve deposits. Intake valve deposits interfere with valve closing and eventually result in valve burning. Such deposits interfere with valve motion and valve sealing, and in addition reduce volumetric efficiency of the engine and limit maximum power. Valve deposits are usually a result of thermal and oxidative unstable fuel or lubricating oil oxidation products. Hard carbonaceous deposits collect in the tubes and runners that conduct ther exhaust gas recirculation (EGR) gases. These deposits are believed to be formed from exhaust particles which are subjected to rapid cooling while mixing with the air-fuel mixture. Reduced EGR flow can result in engine knock and NO.sub.x emission increases. It would therefore be desirable to provide a motor fuel composition which minimizes or overcomes the formation of intake valve deposits.
Various motor fuel formulations comprising polyoxyalkylene reaction product additives have been disclosed which prevent or minimize combustion chamber deposit formation, and hence minimize engine ORI. For example, co-assigned U.S. Pat. No. 4,852,993 filed Aug. 12, 1987 and incorporated herein by reference discloses a motor fuel composition comprising (I) the reaction product of the polyoxyalkylene diamine of co-assigned U.S. Pat. No. 4,747,851, discussed infra, a dibasic acid anhydride, and a hydrocarbyl polyamine, and (II) a mixture comprising polyisobutylene ethylene diamine and polyisobutylene in a hydrocarbon solvent. However, it has been found that a concentrate composition comprising components (I) and (II) precipitates during storage, which is undesirable. Other motor fuel compositions comprising polyoxyalkylene additives to reduce engine ORI include the following references, all incorporated herein by reference:
Co-assigned U.S. Pat. No. 4,747,851, filed Jan. 2, 1987 discloses a novel polyoxyalkylene diamine compound of the formula: ##STR1## where c has a value from about 5-150, b+d has a value from about 5-150, and a+e has a value from about 2-12. Motor fuel compositions comprising the novel polyoxyalkylene diamine, alone or in combination with a polymer/copolymer additive are also disclosed;
Co-assigned U.S. patent application Ser. No. 000,230, filed Jan. 2, 1987 now abandoned discloses a motor fuel composition comprising the reaction product of the polyoxyalkylene diamine of U.S. patent application Ser. No. 000,253, a dibasic acid anhydride, and a hydrocarbyl polyamine. An optional additional polymer/copolymer additive with a molecular weight of 500-3500 may also be employed in conjunction with the reaction product additive;
Co-assigned U.S. Pat. No. 4,659,337 discloses the use of the reaction product of maleic anhydride, a polyether polyamide containing oxyethylene and oxypropylene ether moieties, and a hydrocarbyl polyamine in a gasoline motor fuel to reduce engine ORI and provide carburetor detergency;
Co-assigned U.S. Pat. No. 4,659,336 discloses the use of the mixture of: (i) the reaction product of maleic anhydride, a polyether polyamine containing oxyethylene and oxypropylene ether moieties, and a hydrocarbyl polyamine; and (ii) a polyolefin polymer/copolymer as an additive in motor fuel compositions to reduce engine ORI;
Co-assigned U.S. Pat. No. 4,631,069 discloses an alcohol-containing motor fuel composition which additionally comprises an anti-wear additive which is the reaction product of a dibasic acid anhydride, a polyoxyisopropylene diamine of the formula ##STR2## where x has a value of 2-68, and an n-alkyl-alkylene diamine;
Co-assigned U.S. Pat. No. 4,643,738 discloses a motor fuel composition comprising a deposit-control additive which is the reaction product of a dibasic acid anhydride, a polyoxyisopropylene diamine of the formula ##STR3## where x has a value of 2-50, and an n-alkyl-alkylene diamine;
U.S. Pat. No. 4,604,103 discloses a motor fuel deposit control additive for use in internal combustion engines which maintains cleanliness of the engine intake system without contributing to combustion chamber deposits or engine ORI. The additive disclosed is a hydrocarbyl polyoxyalkylene polyamine ethane of molecular weight range 300-2500 having the formula ##STR4## where R is a hydrocarbyl radical of from 1 to about 30 carbon atoms; R' is selected from methyl and ethyl; x is an integer from 5 to 30; and R" and R'" are independently selected from hydrogen and --(CH.sub.2 CH.sub.2 NH--).sub.y --H where y is an integer from 0-5; and
Co-assigned U.S. Pat. No. 4,581,040 discloses the use of a reaction product as a deposit inhibitor additive in fuel compositions. The reaction product is a condensate product of the process comprising:
(i) reacting a dibasic acid anhydride with a polyoxyisopropylenediamine of the formula ##STR5## where x is a numeral of about 2-50, thereby forming a maleamic acid;
(ii) reacting said maleamic acid with a polyalkylene polyamine, thereby forming a condensate product; and
(iii) recovering said condensate product.
Motor fuel compositions which contain amine additives to control deposition include the following:
U.S. Pat. No. 4,357,148 discloses a motor fuel additive useful in controlling ORI which is the combination of (a) an oil-soluble aliphatic polyamine containing at least one olefinic polymer chain, and (b) a polymer, copolymer, or corresponding hydrogenated polymer or copolymer of a C.sub.2 -C.sub.6 mono olefin with a molecular weight of 500-1500;
U.S. Pat. No. 4,166,726 discloses a fuel additive which is the combination of (i) the reaction product of an alkylphenol, an aldehyde, and an amine, and (ii) a polyalkylene amine;
U.S. Pat. No. 3,960,515 and U.S. Pat. No. 3,898,056 disclose the use of a mixture of high and low molecular weight hydrocarbyl amines as a detergent and dispersant in motor fuel compositions; and
U.S. Pat. No. 3,438,757 discloses the use of hydrocarbyl amines and polyamines with a molecular weight range of 450-10,000, alone or in combination with a lubricating mineral oil, as a detergent for motor fuel compositions.
An object of this invention to provide a reaction product composition which may be employed as an ORI-reducing additive in motor fuel compositions. Another object of this invention is to provide a method of blending the reaction product composition of the instant invention, either alone or in combination with the hereindescribed polyolefin polymer/copolymer, into a base motor fuel composition. Another object of this invention is to provide a motor fuel composition which is deposit-resistant and exhibits ORI-inhibition when employed in an internal combustion engine. Yet another object of this invention is to provide a concentrate composition which may be added to a motor fuel to provide motor fuel compositions of the instant invention.
It is a feature of motor fuel compositions of the instant invention that combustion chamber deposit formation is minimized, with concomitant reduction of engine ORI. It is another feature of this invention that such motor fuel composition are deposit-resistant and specifically exhibit reduced intake valve deposit formation. It is yet another feature of this invention that the concentrate composition of this invention may be admixed with a motor fuel to minimize combustion chamber deposit formation, and hence inhibit engine ORI.
It is an advantage of this invention that motor fuel compositions of the instant invention exhibit reduced engine ORI and reduced valve deposit formation. It is another advantage of this invention that concentrate compositions of the instant invention exhibit esistance to precipitation, and thereby have enhanced storage stability.